Every competent TOTP implementation has backup codes. Use one of your backup codes when your phone breaks.

You did write them down like the site told you to, right?

Even if a site doesn't offer backup codes, you can extract the TOTP secret from the QR code, or most authenticator apps, quite easily, and then write it down.

It's more secure to only save the backup codes though since they have a limited number of uses, while the TOTP secret has unlimited uses.

I know you said competent, so this doesn't apply to the service I used yesterday, but it blew my mind. I lost access to TOTP for a service, but no big deal, I'm a good person who kept the backup codes. The codes are all 4 digits and the service wants a 6 digit code!

Luckily it is some lame work account that someone else can unlock to get me back in. I couldn't believe that the backup codes provided are now obsolete!

Damn, you're lucky it's not something important. Especially with accounts for things like Google or Facebook/Instagram where they boast about not having any human support and you are totally shit-out-of-luck if you can't get in.

Except Google. Google backup codes are near useless because a Google backup code will let you log in, but won't allow you to disable 2 factor or add a new 2 factor device - meaning if you ever lose a 2 factor device and have to use a backup code, there is no way to recover your account.

Really? I'd imagine you'd need two codes (one for the login, one for access to your 2FA settings), but not being able to recover at all using them seems horrible!

It just gives some error like "this login method is not allowed for this action" or similar.

Interesting. I can't confirm though - I personally changed my 2FA device 2 weeks ago using a backup code. I couldn't find old yubikey that I used as 2FA for google, decided to regain access with a backup code and add my new yubikey, and it worked flawlessly. It probably helped that I used the same machine as always. Google does a lot of undocumented heuristics in the background, and you either get additional verification or not.

Yes, same machine helped, it's definitely one of the factors it uses.

I have a near-20-year Google account I can't access because I lost the 2FA number. I have the username, password and recovery email. But that isn't enough, apparently.

Authy solves this by putting all the TOTP keys behind a master password and then backing it up online, so you can get up and running on a different device quickly. It's the same trade-off as a password manager, where your eggs are all in one basket but hopefully it's a secure basket.

QRcode TOTP, and print the QRcode out and store it in a safe/offline.

That way you can easily re add the 2fa token to a replacement device.

Have a paper backup of the codes?

And carry it with you at all times, of course.

All those proponents of a 'proper security with a strict 2FA' never been out of country, mugged, in an accident or in any combination of these.

Hell, if I just lose my wallet and would be forced to reissue the IDs and SIM (retaining the number!) it would take weeks to be back 'online'.

You can enroll multiple devices using the same TOTP QR code, just scan it more than once. They will generate the same code sequence and the site won’t know the difference.

You can even save the QR code and enroll a new device later if you want.

> You can enroll multiple devices using the same

You could even save it in an application like KeepassXC. Then you turn on the TOTP mode and presto, you have another TOTP device

bitwarden has TOTP built in as well. Apple has it built into their platform, but its tougher to use and only works with Chrome if you use windows too.....

This is why it’s good to also enroll a hardware key or two if the site/service offers the option. One could for example have a “rescue” YubiKey stuck away in their closet that could be added. MacBooks with Touch ID can also work if you have one of those handy — some sites allow enrolling it via Safari and IIRC Chrome and its myriad clones present Touch ID as a generic key that can be enrolled anywhere WebAuthN is supported.

For extra assurance get a hardware key that supports NFC so it can be used with your phone (and some laptops) even if it can’t be plugged in for some reason.

Multi-pronged 2FA also enables things like being able to remove a key from your account without issue if for example one turns up missing while traveling.